test: add it tests for micrometer core

[caalador]

add TestBench tests for the
micrometer core feature.

[heruan]

Could we move it to a profile so the unit build stays license-free, while CI (which sets the key) still runs it by default?

<profiles>
  <profile>
    <id>it</id>
    <activation>
      <property><name>!skipIt</name></property>
    </activation>
    <modules>
      <module>observability-kit-micrometer-test</module>
    </modules>
  </profile>
</profiles>

IT builds by default (CI keeps running it), but mvn verify -DskipIt (or building just the core modules) skips ITs. The workflow can stay as-is.

[caalador]

Renamed and profile added

[heruan]

Just noticed: I would rename the outer test module to observability-kit-test so it can include not just micrometer tests but possibly other integrations later, e.g.

• observability-kit-test-micrometer
• observability-kit-test-spring
• observability-kit-test-prometheus (e.g. docker compose, etc.)

[caalador]

Done